1. Field of the Invention
The present invention relates to a manufacturing method for a semiconductor wafer having an epitaxial layer.
2. Description of the Related Art
A silicon wafer is known as a popular semiconductor wafer. One example of the silicon wafer is a prime wafer, which is generally a single-crystal silicon substrate. Another example of the silicon wafer is an epitaxial wafer. The epitaxial wafer is a wafer constructed such that films of a silicon single-crystal having the same crystal structure are deposited on a prime wafer according to the regular arrangement of silicon atoms.
A known manufacturing method of the epitaxial wafer includes the step of depositing a silicon thin film on a completed prime wafer by an epitaxial growth process. Specifically, the prime wafer is heated to approximately 1150 degrees C. in a process chamber, and a monosilane gas and a hydrogen gas are introduced into the chamber. The monosilane gas is pyrolyzed, with the result that silicon atoms are successively deposited on the prime wafer according to the crystal structure of the prime wafer. Consequently, a single-crystal silicon thin film grows on the prime wafer.
The epitaxial wafer obtained by the above-described manufacturing method has a crystal layer with less impurities and defects formed on the wafer surface thereof if the epitaxial wafer is compared with the prime wafer. That is, the layer, where semiconductor elements will be formed, of the epitaxial wafer has a high-quality as compared with the prime wafer, and therefore, it is possible for the epitaxial wafer to exhibit high reliability as a semiconductor device after the semiconductor elements are formed.
Japanese Patent Application Publication (Kokai) No. 7-6986 discloses a method of grinding the semiconductor wafer with high precision to a desired thickness.